[PATCH v1 0/4] Introduce mtdblock device

[Frieder Schrempf]

Hi Alexey,

On 27.02.24 11:04, Alexey Romanov wrote:
> Hello!
> 
> This series adds support for the mtdblock device, which
> allows to read/write data block by block. For example,
> it can now be used for BCB or Android AB command:
> 
>   $ bcb load mtd 0 part_name
> 
> Tested only on SPI NAND, so bind is made only for
> SPI NAND drivers.

I don't know much about Android, but as far as I understand you are
trying to store dynamic, boot-related information on the MTD device.

This might be acceptable if the underlying device is a NOR flash, but
for any type of NAND device it sounds like a rather bad idea.

NAND devices need some kind of FTL (flash translation layer) in order to
work reliably. Using a block filesystem directly on the NAND MTD device
will cause problems as soon as any bad blocks or bit flips occur.

People are therefore discouraged to use mtdblock on NAND and in the
kernel there is even a warning if you try to mount a NAND mtdblock
partition.

Maybe you should reconsider this and look into how to use UBIFS as a
FTL. On the other hand I'm not quite sure if the UBIFS layer in U-Boot
is really stable and maintained. So this might not be a good idea either.

Anyway, I'm against implementing mtdblock for SPI NAND (or any other NAND).

Best regards
Frieder